border-1px($color)
  position: relative
  &:after
    display: block
    position: absolute
    left: 0
    bottom: 0
    width: 100%
    border-bottom: 1px solid $color
    content: ''

border-3px(val)
  border: val solid red

border-radius(val)
  border-radius: val

border-none()
  position: relative
  &:after
    display: none

bg-image($url)
  background-image: url($url+"@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3) , (min-device-pixel-ratio: 3)
    background-image: url($url+"@3x.png")
